1. Field of the Invention
The present invention relates to an ink-jet printhead package. More particularly, the present invention relates to an ink-jet printhead package having a simplified structure that facilitates cleaning of a printhead, e.g., by wiping with a blade.
2. Description of the Related Art
Typically, ink-jet printheads are devices for printing a predetermined color image by ejecting a small volume droplet of printing ink at a desired position on a recording sheet, textile, or the like. Ink-jet printheads are largely categorized into two types depending on which mechanism is used to eject an ink droplet. A first type of ink-jet printhead is a thermally driven ink-jet printhead, in which a heat source is employed to form and expand bubbles in ink causing ink droplets to be ejected. A second type of ink-jet printhead is a piezoelectrically driven ink-jet printhead, in which a piezolectric crystal bends to exert pressure on ink causing ink droplets to be ejected.
Ink-jet printheads are typically manufactured in a chip shape using various methods, including a semiconductor manufacturing process. In addition, a packaging is required to mount the manufactured printhead chip in a printer.
FIG. 1 illustrates a conventional ink-jet printhead package. Referring to FIG. 1, the conventional ink-jet printhead package includes a passage unit 16 including a nozzle plate 13, on which a plurality of nozzles 11 is arranged in rows; a passage formation plate 14, on which a plurality of pressure chambers corresponding to each of the plurality of nozzles 11 is formed; and an elastic plate 15, which transfers vibration of a piezoelectric actuator 12, which is fixed in a casing 17, to change the volumes of the pressure chambers. The passage unit 16 is fixed in the casing 17 by a head cover 19 having a window for exposing the nozzles 11.
In the conventional ink-jet printhead package, when a portion of the ink droplets ejected from the nozzles 11 remains on a surface of the nozzle plate 13, the ink droplets remaining on the surface of the nozzle plate 13 mix with ink of other colors, or change an ejection direction of the ink droplets, thereby resulting in a lower printing quality. Thus, a wiping blade is typically used to remove the ink remaining on the surface of the nozzle plate 13. When the printhead package moves in a reciprocating motion, the wiping blade contacts the surface of the nozzle plate 13 and wipes the ink remaining on the surface.
However, in this conventional ink-jet printhead package, an entire periphery of the surface of the nozzle plate 13 is covered with the head cover 19. Thus, a wiping blade, which can be somewhat elastically-transformed, is not able to closely contact a region of the nozzle plate 13 near the head cover 19. Accordingly, the ink remaining on the nozzle plate 13 cannot be sufficiently removed.
As such, ink-jet printhead packages that attempt to prevent the above problems have been developed. An example of another conventional ink-jet printhead package is shown in FIGS. 2 through 4. FIG. 2 illustrates a perspective view of a conventional ink-jet printhead package. FIG. 3 illustrates a cross-sectional view, taken in a direction A, of a wiping blade and a head cover shown in FIG. 2. FIG. 4 illustrates a cross-sectional view, taken in a direction B, of the wiping blade and the head cover shown in FIG. 2;
The conventional ink-jet printhead package shown in FIGS. 2 through 4 includes a casing 32, a passage unit 34 having a nozzle plate 41, on which a plurality of nozzles 43 is formed, and a head cover 35 that secures the passage unit 34 in the casing 32.
The head cover 35 has four sidewalls 50. Each of the four sidewalls 50 contact a corresponding side of the casing 32. An overlap portion 51 of the head cover 35 covers a portion of the surface of the nozzle plate 41. The overlap portion 51 is provided only on the sidewalls 50 of the head cover 35 that are perpendicular to a wiping direction (direction of arrow B). No overlap portion is provided on the sidewalls 50 of the head cover 35 that are parallel to the wiping direction (direction of arrow A), thereby forming a wiping space 52.
Referring now to FIGS. 3 and 4, in the conventional ink-jet printhead package having the above structure, when a surface of the nozzle plate 41 is wiped with a wiping blade 56, the wiping blade 56 contacts the entire width of the surface of the nozzle plate 41, so that any ink K remaining on the surface of the nozzle plate 41 can be easily removed.
However, in the aforementioned ink-jet printhead package, as shown in FIG. 4, the overlap portion 51 of the head cover 35 is on a portion of the nozzle plate 41 to secure the passage unit 34, and the nozzle plate 41, in the casing 32. Due to this contact, ink can spread between the nozzle plate 41 and the overlap portion 51 and may be subsequently scattered on an object to be printed during a printing operation, resulting in a lower printing quality. In addition, a step, i.e., a difference in height, is formed between the surface of the nozzle plate 41 and the overlap portion 51. As a result, an unstable motion of the wiping blade 56 occurs. In addition, ink that is not removed by the wiping blade 56 is stacked in a corner portion of the surface of the nozzle plate 41 adjacent to the step formed by the overlap portion 51 of the head cover 35.